A national immunization program for infants in
Until 1999, Israel was considered a country with intermediate hepatitis A virus endemicity. Although the overall incidence has been progressively decreasing since the 1960s, the annual reported incidence during the 1992-1998 period ranged from 33 to 70 per 100,000 population, with marked fluctuations. Reports of outbreaks, especially those involving young children, increased. Because most young children have asymptomatic or unrecognized infection, they play an important role in hepatitis A virus transmission as a source of infection. Therefore, routine childhood vaccination would theoretically prevent infection in age groups that account for a substantial proportion of cases, eliminate a major source of infection for other children and adults, and eventually prevent infections in older persons as vaccinated children grow to adulthood, because immunity to hepatitis A virus by vaccination is long-lasting.
Health officials in
Ron Dagan, MD, of Ben-Gurion University of the Negev, Beer-Sheva, Israel, and colleagues examined the impact of the toddlers-only vaccination program of hepatitis A disease in all ages in the 5.5 years following initiation of the program. Overall vaccine coverage in
A decline in disease rates was observed before 1999 among the Jewish but not the non-Jewish population. The researchers found that after initiation of the program, a sharp decrease in disease rates was observed in both populations. The annual hepatitis A incidence rate of 2.2 to 2.5 per 100,000 during 2002-2004 represents a 95 percent or greater reduction for each year with respect to the average incidence during 1993-1998 (50.4 per 100,000). For children aged 1 through 4 years, a 98.2 percent reduction in hepatitis A disease was observed in 2002-2004, compared with the pre-vaccination period. However, a sharp decline was also observed in all other age groups (84.3 percent [less than 1 year], 96.5 percent [5-9 years], 95.2 percent [10-14 years], 91.3 percent [15-44 years], 90.6 percent [45-64 years], and 77.3 percent [65 years or older]). Among the Jewish population in the
In the next decade, many regions worldwide will move from a state of high endemicity to a state of intermediate endemicity. The Israeli program of universal toddlers-only vaccination can serve as a paradigm of a simplified model of effective vaccination for both developed and developing countries, the authors conclude.
Reference: JAMA. 2005;294:202210
Source: American Medical Association